Astroglia cells are the largest population cells in the brain; through secreting kinds of chemokine and factors, it gives glia cells versatile function in the central nerve system. Astroglia can be supportive to neuron by releasing trophic factors, chelating ROS, proving nutrition and removing toxic glutamine produced by neuron itself. One chemokine – CCL5/RANTES has been identified supporting neuronal neurite out growth, branching, and Ca2+ influx by us. Brains from CCL5/RANTES knockout mice also showed reduced dendritic spines numbers in our preliminary data. Some finding also indicates CCL5 and its corresponding receptor CCR5 activity can interfere neuronal stem cell differentiation. Thus, the supporting role of astroglia cells to neurons is our interest to investigate. The cellular mechanism of CCL5 activating neurons in axon growth and spine formation or neuron differentiation is first to ask in this proposal (Aim-1). There are two signaling pathway have been identified regulating neuronal axongenesis. One is phosphatidyl - inositol 3-kinase (PI3-kinase)/Akt/glycogen synthase kinase-3β (GSK-3β)/collapsing response mediator protein-2 pathway which response for axon initiation and elongation; another is Rho family small GTPase and the Par3/Par6/atypical protein kinase C complex which plays as a positive feedback loop signal maintaining axon growth. CCL5 treated T-cells shown increased 5’ AMP-activated protein kinase (AMPK) and GSK-3β phosphorylation in mins. AMPK plays a crucial role in neurogenesis, neuronal polarization and survival. AMPK activity has shown correlates to making a decision role in axon initiation and mediated PI3K vesicles binding to kinesin light chain (KLC) performing axongenesis process. We will investigate the correlation of CCL5/RANTES and AMPK, GSK-3β activity in neuronal cells. Preliminary results found increased phosphorylation of AMPK in CCR5 knockout mice brain and reduced glucose uptake transporter in CCL5 knockout brain comparing wildtype mice. These suggest a regulatory role of CCL5/CCR5 in AMPK activity and intracellular energy homeostasis. A further investigation helps us to reveal the cellular mechanism of CCL5 (Aim-2). To reveal the direct contribution of CCL5 in neuron functions, live cell image and animals experiments will carry out in this proposal also (Aim-1 & 3). Intracellular vesicles in neuron will labeled and traffic along axon with or without CCL5 to investigate CCL5 function on neuron maturation. CCL5 knockout animals will also employee a rescue experiment to confirm CCL5’s function on neuron growth and activity. Besides of targeting on neuron in other studies, this proposal aims on neuron’s biggest neighbor – astroglia cells which can provide a rich environment for neuron growth and guidance neuron by releasing proper trophic factors. With this study, we will be able to find a possible treatment to neurodegeneration and important scientific knowledge in neuron-glia interaction and axongenesis mechanism.
|Effective start/end date||2/1/14 → 10/31/14|